Converter with shell sized to endplates

The present invention relates to producing catalytic converters. More particularly, the invention relates to producing catalytic converters, the housing or canister of which is sized down onto endplates. An exhaust systems converter comprising an endplates, with an annular rings, positioned around both annular sides of a catalyst, an intumescent mat support wrapped around the catalyst and the annular rings, and an oversized shell which is sized to the endplates and welded in place.